Global Environmental Problems

Spring 2006

Problem Set #1

Due: 8 February

1.

Energy consumption data are given by WRI, EIA, BP, and many other sources. Select any two of these sources, find total world oil, gas, and coal consumption in the same (and most recent) year, and convert each into EJ/y.

Do the two sources agree perfectly? How large are the differences (in percent)?

Sources gives data in various units, including Quads (10¹⁵ BTU), metric tons of oil equivalent (toe), barrels of oil (bbl), and cubic meters or cubic feet of gas, and short tons of coal. Assume 41.868 GJ/toe, 0.1364 toe/bbl for oil, 1100 m³/toe for gas, and 18 MJ/kg for coal.

2.

In chapter I of Harte, read problem 6 ("The Greens We Eat") and do exercises 1, 2, and 3, with the following modifications:

In exercise 1, use the current world population.

In exercise 2, use figures for the average American, who consumes (or discards) 3800 Calories of food per day, of which one-third is derived from animals, as well as current world population.

In exercise 3, use the fossil-fuel consumption you calculated in problem 1 rather than the old (1980) data in Harte.

3.

In an article in the Washington Post ("Who Will Feed China?"), Lester Brown wrote that the Yellow River annually transports 1.6 billion tons of topsoil to the sea. This certainly is an impressive number, but it’s not something that most people can comprehend. To make it more comprehensible, how long would it take, at this rate of erosion, to remove one foot of topsoil from the entire Yellow River basin? Assume that the Yellow River basin has an area of about 60 million hectares (Mha) and that the density of topsoil is about 1.6 tons per cubic meter (1600 kg/m³). 

4.

Read the following article by Jeffrey Ball, "Burial Plan Deep in the Sahara," Wall Street Journal, 4 February 2005, and answer the following questions:

A.

In the first four paragraphs, the article gives the cost of the carbon-sequestration portion of the project, the amount of carbon dioxide sequestered annually, and the length of the project. Based on this information, what is the average cost of carbon sequestration, in dollars per ton of CO₂?

B.

In the climate-change community, these costs are more commonly given in dollars per ton of carbon. Convert your answer in part A into these units.

C.

At the end of the four paragraph, the author states that the amount sequestered is "about as much CO₂ annually as 100,000 sport-utility vehicles emit." Confirm this statement by estimating the CO₂ emissions of 100,000 SUVs. Is this author correct?

You will need to estimate: (i) the average number of miles driven per year; (ii) the number of miles driven per gallon of gasoline consumed, (iii) the density of gasoline, and (iv) the carbon content of gasoline. For (iii) and (iv), you may either find values by searching the web or make an informed guess. To make an informed guess about (iii), is gasoline more or less dense than water? how much more or less? For (iv), note that gasoline is mostly octane (C₈H₁₈).

5.

About 16 million people live in the Chesapeake Bay watershed, which covers large parts of New York, Pennsylvania, Maryland, Delaware, and Virginia. 

A.

Based on what you know about the number of cars per person, the number of miles each car is driven, the number of miles between oil changes, and the amount of motor oil added during each oil change, estimate the amount of oil that is discharged from automobiles in the Chesapeake Bay watershed each year.

B.

It is estimated about one quarter of this oil is released into the environment, either through leaks and evaporation or illegal disposal of waste oil. Compare the annual release of oil in the watershed to the amount released by the Exxon Valdez (11 million gallons, of which 6 million were recovered).